NEW YORK — A big gain in the job market is pushing the stock market past new milestones. The Dow Jones industrial average crossed 15,000 for the first time early Friday, and the Standard and Poor’s 500 index, a broader market measure, broke through 1,600. The Dow was up 136 points to 14,967, an increase of 0.9 percent, as of 3:11 p.m. The S&P 500 index surged 16 points, or 1 percent, to 1,613. The driver was jobs. U.S. employers added 165,000 of them in April and more in February and March than previously estimated. The unemployment rate fell to the lowest level in four years, 7.5 percent. The surge in U.S. hiring comes after weeks of conflicting signals about the strength of the global economy. The unexpectedly strong numbers jolted markets higher from the start of trading. “There’s euphoria today,” said Stephen Carl, the head equity trader at The Williams Capital Group. “That’s what you’d have to call it.” On the floor of the New York Stock Exchange, brokers sported baseball caps emblazoned with “Dow 15,000.”